The ability to introduce foreign DNA into eukaryotic host cells is one of the principle tools of recombinant DNA technology. Methods for transfecting eukaryotic host cells with foreign DNA can be broadly grouped into four categories: (1) direct introduction of cloned DNA by microinjection or microparticle bombardment; (2) use of viral vectors; (3) encapsulation within a carrier system; and (4) use of facilitators such as calcium phosphate and diethylaminoethyl (DEAE)-dextran. Of the reagents used as facilitators of DNA transfection, calcium phosphate remains the most widely used because of its simplicity and general effectiveness for a wide variety of cell types.
The original protocol for calcium phosphate transfection was described by Graham and van der Eb, Virology, 52:456-467 (1973). This method was modified by Wigler et al., Proc. Natl. Acad. Sci., 76:1373-1376 (1979) and by Chen and Okayarea, Mol. Cell. Biol., 7:2745-2752 (1987). Nevertheless, the original and modified protocols yield relatively low transfection efficiencies and expression in experiments geared towards transient or stable DNA transfer. Accordingly, there is still a need for an improved method of calcium phosphate transfection. In addition, there is a need for methods of calcium phosphate transfection in suspension culture, particularly in the area of large scale suspension culture.
This and other objects will be apparent to those skilled in the art.